Semiconductor device
The present invention provides a semiconductor device, including a substrate, two gate structures disposed on a channel region of the substrate, an epitaxial layer disposed in the substrate between two gate structures, a first dislocation disposed in the epitaxial layer, wherein the profile of the first dislocation has at least two non-parallel slanting lines, and a second dislocation disposed adjacent to a top surface of the epitaxial layer, and the profile of the second dislocation has at least two non-parallel slanting lines.
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This application is a continuation application of U.S. patent application Ser. No. 15/628,658 filed Jun. 21, 2017, which is a divisional application of U.S. patent application Ser. No. 14/960,444 filed Dec. 7, 2015, which is herein incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to the field of semiconductor technology, and more particularly, to a mechanism for the improving the stress efficiency in the source region in a semiconductor device.
2. Description of the Prior Art
The semiconductor integrated circuit (IC) industry has experienced rapid growth. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC manufacturing are needed.
For example, as semiconductor devices, such as a metal-oxide-semiconductor field-effect transistors (MOSFETs), are scaled down through various technology nodes, strained source/drain features (e.g., stressor regions) have been implemented to enhance carrier mobility and improve device performance. Stress distorts or strains the semiconductor crystal lattice, which affects the band alignment and charge transport properties of the semiconductor. By controlling the magnitude and distribution of stress in a finished device, manufacturers can increase carrier mobility and improve device performance. Although existing approaches to forming stressor regions for IC devices have been generally adequate for their intended purposes, they have not been entirely satisfactory in all respects.
SUMMARY OF THE INVENTIONThe present invention provides a semiconductor device, comprising a substrate, two gate structures disposed on a channel region of the substrate, an epitaxial layer disposed in the substrate between two gate structures, and a first dislocation disposed in the epitaxial layer, wherein the profile of the first dislocation has at least two non-parallel slanting lines, and a second dislocation disposed adjacent to a top surface of the epitaxial layer, and the profile of the second dislocation has at least two non-parallel slanting lines.
The present invention further provides a semiconductor device, comprising a substrate, two gate structures disposed on a channel region of the substrate, and two spacers disposed on two sides of each gate structure, an epitaxial layer disposed in the substrate between two gate structures, and a second dislocation disposed adjacent to a top surface of the epitaxial layer, the second dislocation contacting the spacer directly, the profile of the second dislocation having at least two first lines and at least two second lines, and the first line not being parallel to the second line.
The present invention further provides a method for forming a semiconductor device, comprising the following steps: firstly, a substrate is provided, next, two gate structures are formed on a channel region of the substrate, afterwards, an epitaxial layer is formed in the substrate between two gate structures, wherein the epitaxial layer comprises a first dislocation disposed therein, the profile of the first dislocation is a reverse V shaped profile, a second dislocation is disposed adjacent to a top surface of the epitaxial layer, and the profile of the second dislocation is a V shaped profile.
The embodiments of processes and structures of the present invention provide a mechanism for improving mobility of carriers. The dislocations in the source and drain regions and the tensile stress created by the doped epitaxial materials next to the channel region of a transistor both contribute to the tensile stress in the channel region. In particular, the tensile stress is good for improving the mobility of carriers of an NMOS transistor. In the present invention, except for the first dislocation being formed within the epitaxial layer, at least one second dislocation is formed near the surface of the epitaxial layer, and both the two dislocations contribute to the tensile stress, thereby further improving the device performance.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
To provide a better understanding of the present invention to users skilled in the technology of the present invention, preferred embodiments are detailed as follows. The preferred embodiments of the present invention are illustrated in the accompanying drawings with numbered elements to clarify the contents and the effects to be achieved.
Please note that the figures are only for illustration and the figures may not be to scale. The scale may be further modified according to different design considerations. When referring to the words “up” or “down” that describe the relationship between components in the text, it is well known in the art and should be clearly understood that these words refer to relative positions that can be inverted to obtain a similar structure, and these structures should therefore not be precluded from the scope of the claims in the present invention.
Please refer to
Referring to
The substrate 210 includes various doped regions depending on design requirements as known in the art (e.g., p-type wells or n-type wells). The doped regions are doped with p-type dopants, such as boron or BF2, and/or n-type dopants, such as phosphorus or arsenic. The doped regions include various active regions, such as regions configured for an N-type metal-oxide-semiconductor transistor (referred to as an NMOS) and regions configured for a P-type metal-oxide-semiconductor transistor (referred to as a PMOS).
It is noteworthy that the semiconductor device described below are disposed within the NMOS transistor region, in other words, the semiconductor device belongs to a NMOS transistor device. The reason is the dislocation that formed in the following steps will provide a tensile stress, the tensile stress is good for improving the performance of a NMOS transistor, but not suitable for a PMOS transistor, it will be described again in the following paragraphs. Of course, the semiconductor device of the present invention may further comprise a PMOS transistor, however, the PMOS transistor is not for by the method 100 shown in
In some embodiments, the substrate 210 includes an isolation region to define and isolate various active regions of the substrate 210. The isolation region utilizes isolation technology, such as shallow trench isolation (STI) or local oxidation of silicon (LOCOS), to define and electrically isolate the various regions. The isolation region includes silicon oxide, silicon nitride, silicon oxynitride, other suitable materials, or combinations thereof.
With further reference to
The gate structure 220 includes various gate material layers. In the present embodiment, the gate structure 220 includes a gate stack 222, which includes one or more gate dielectric layer and a gate electrode. In some embodiments, the gate structure 220 also includes gate spacers 224 disposed on sidewalls of the gate stack 222.
The gate stack 222 is formed over the substrate 210 to a suitable thickness. In an example, the gate stack 222 includes a polycrystalline silicon (or polysilicon) layer. In some embodiments, the polysilicon layer is doped for proper conductivity. Alternatively, the polysilicon is not necessarily doped. In another example, the gate stack 222 includes a conductive layer having a proper work function; therefore, the gate stack 222 is also referred to as a work function layer. The work function layer includes a suitable material, such that the layer is tuned to have a proper work function for enhanced performance of the device. For example, if an N-type work function metal (N-metal) for an NMOS device is desired, Ta, TiAl, TiAlN, or TaCN, is used. In some embodiments, the work function layer includes doped conducting oxide materials. In some embodiments, the gate stack 222 includes other conductive materials, such as aluminum, copper, tungsten, metal alloys, metal silicide, other suitable materials, and/or combinations thereof. In some embodiments, the gate stack 222 includes multiple layers. In some embodiments, the gate stack 222 is formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), high density plasma CVD (HDPCVD), plating, other suitable methods, and/or combinations thereof.
The gate spacers 224 are formed over the substrate 210 by any suitable process to any suitable thickness. The gate spacers 224 include a dielectric material, such as silicon nitride, silicon oxide, silicon oxynitride, other suitable materials, and/or combinations thereof.
Referring to
Referring to
In some embodiments, a patterned photoresist layer is utilized to define where the amorphized region 232 is formed and to protect other regions of the semiconductor device 200 from implantation damage. For example, the PMOS regions are protected. In addition, the patterned photoresist layer exposes the source/drain regions, such that the source/drain regions are exposed to the PAI process 230 (forming amorphized region 232) while the gate structure 220 and other portions of the semiconductor device 200 are protected from the PAI process 230. Alternatively, a patterned hard mask layer, such as a SiN or SiON layer, is utilized to define the amorphized region. In some embodiments, the patterned photoresist layer or the patterned hard mask layer is part of the current manufacturing process, for example lightly-doped drains (LDD) or source/drain formation, thereby minimizing cost as no additional photoresist layer or hard mask is required for the PAI process 230. After the PAI process is performed, the photoresist on substrate 210 is removed.
Referring to
During the annealing process 250, as the substrate 210 recrystallizes, at least one first dislocation 260 is formed in the re-crystallization region 252. In some embodiments, the dislocations 260 are formed in the [111] direction. In some embodiments, the [111] direction has an angle in a range from about 45 to about 65 degrees, the angle being measured with respect to an axis parallel to a surface of the substrate 210.
Referring to
Afterwards, as shown in
Afterwards, as shown in
It is noteworthy that after the epitaxial layer 285 is formed, the first dislocation 260 is extended from the re-crystallization region 252 into the epitaxial layer 285. Therefore, the profile of the first dislocation 260 includes two non-parallel slanting lines. Preferably, the intersection of the two non-parallel slanting lines or its extending line is disposed above the first dislocation 260, so the first dislocation 260 has a reverse-V shaped profile in the epitaxial layer 285. Besides, the applicant found that during the formation of the epitaxial layer 285, if the distance between two gate structures 220 is small enough, since the epitaxial layer 285 is not easy to be formed on the surface of the spacer 224 and the epitaxial layer 285 will grow along a specific crystal surface, a second dislocation 287 can easily be formed near the top surface 288 of the epitaxial layer 285 while the epitaxial layer 285 touches the spacer 224. The second dislocation 287 also comprises two non-parallel slanting lines. Preferably, the intersection of the two non-parallel slanting lines or its extending line is disposed below the second dislocation 287, so the second dislocation 287 has a V shaped profile in the epitaxial layer 285. In addition, the second dislocation 287 contacts the spacer 224 directly. In one embodiment, as shown in
In another embodiment, as shown in
In an embodiment, as shown in
Finally, as shown in
In another case, as shown in
The embodiments of processes and structures described above provide mechanisms for improving mobility of carriers. The dislocations in the source and drain regions and the tensile stress created by the doped epitaxial materials next to the channel region of a transistor both contribute to the tensile stress in the channel region. In particular, the tensile stress is good for improving the mobility of carriers of an NMOS transistor. In the present invention, except for the first dislocation being formed within the epitaxial layer, at least one second dislocation is formed near the surface of the epitaxial layer, and both the two dislocations contribute to the tensile stress, thereby further improving the device performance.
Besides,
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A semiconductor device, comprising:
- a substrate;
- two gate structures disposed on the substrate;
- an epitaxial layer disposed in the substrate between two gate structures;
- a second dislocation disposed adjacent to a top surface of the epitaxial layer, and the profile of the second dislocation has at least two non-parallel slanting lines, and the two non-parallel slanting lines compose a V profile;
- a first dislocation disposed in the epitaxial layer, wherein the profile of the first dislocation has at least two non-parallel slanting lines, and the two non-parallel slanting lines compose a reverse V profile, and wherein the first dislocation does not contact a top surface of the epitaxial layer directly, and an intersection point of the at least two non-parallel slanting lines of the first dislocation is disposed in the epitaxial layer, wherein the intersection point is disposed below the top surface of the epitaxial layer; and
- a contact structure directly contacts the top surface of the epitaxial layer, wherein part of the contact structure is disposed lower than a top surface of the substrate.
2. The semiconductor device of claim 1, wherein the contact structure comprises silicide.
3. The semiconductor device of claim 1, wherein the contact structure has a bottommost surface with a V-shaped profile.
4. The semiconductor device of claim 3, wherein the bottommost surface of the contact structure directly contact with the second dislocation.
5. The semiconductor device of claim 1, wherein the gate structure is a gate structure of an n-type metal-oxide-silicon (NMOS) field-effect transistor (FET).
6. The semiconductor device of claim 1, wherein the material of the epitaxial layer includes SiC, SiP, or SiCP.
7. The semiconductor device of claim 1, further comprising two spacers each respectively disposed on two sides of each gate structure, wherein the second dislocation contacts the spacer directly.
8. A semiconductor device, comprising:
- a substrate;
- two gate structures disposed on the substrate;
- an epitaxial layer disposed in the substrate between two gate structures, wherein a bottom portion of the epitaxial layer is larger than a top portion thereof;
- a second dislocation disposed adjacent to a top surface of the epitaxial layer, and the profile of the second dislocation has at least two non-parallel slanting lines, and the two non-parallel slanting lines compose a V profile, and an intersection point of the at least two non-parallel slanting lines of the second dislocation is disposed in the epitaxial layer, wherein the intersection point is disposed below the top surface of the epitaxial layer; and
- a contact structure directly contacts the top surface of the epitaxial layer, wherein part of the contact structure is disposed lower than a top surface of the substrate.
9. The semiconductor device of claim 8, wherein the contact structure comprises silicide.
10. The semiconductor device of claim 8, wherein the contact structure has a bottommost surface with a V-shaped profile.
11. The semiconductor device of claim 10, wherein the bottommost surface of the contact structure directly contact with the second dislocation.
12. The semiconductor device of claim 8, wherein the gate structure is a gate structure of an n-type metal-oxide-silicon (NMOS) field-effect transistor (FET).
13. The semiconductor device of claim 8, wherein the material of the epitaxial layer includes SiC, SiP, or SiCP.
14. The semiconductor device of claim 8, further comprising two spacers each respectively disposed on two sides of each gate structure, wherein the second dislocation contacts the spacer directly.
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Type: Grant
Filed: Dec 5, 2017
Date of Patent: Jun 11, 2019
Patent Publication Number: 20180097109
Assignee: UNITED MICROELECTRONICS CORP. (Hsin-Chu, Taiwan)
Inventors: En-Chiuan Liou (Tainan), Yu-Cheng Tung (Kaohsiung)
Primary Examiner: Charles D Garber
Assistant Examiner: Alia Sabur
Application Number: 15/832,755
International Classification: H01L 29/32 (20060101); H01L 29/34 (20060101); H01L 29/66 (20060101); H01L 29/78 (20060101); H01L 29/08 (20060101); H01L 29/16 (20060101); H01L 29/161 (20060101); H01L 29/165 (20060101); H01L 29/24 (20060101); H01L 21/02 (20060101); H01L 21/265 (20060101); H01L 21/324 (20060101);